The catalyst prepared based on gold catalyst was used for the oxidation reaction of glycerol using molecular oxygen as an oxidant. The resulting products are carboxylic acids, which are expected to be high value-added and highly functional molecules. The reaction was carried out using both batch and flow reactors. Particular emphasis was placed on the development of catalysts suitable for flow reactors, and we have found catalysts with both high activity and long life. Investigation of the reaction mechanism was focused on the Au/Al₂O₃ catalyst, clarifying the effect of added alkali and proposing a mechanism by which oxygen is activated on the catalyst. The use of high-resolution electron microscopy has revealed the state of other noble metals complexed with gold in the nanoparticle catalysts, which has also enabled a discussion of their influence on the reaction.

Conversion of heavy oil to more useful light oil is becoming increasingly important. Mild hydrocracking (MHC) in a hydrodesulfurization unit is a potential method. Although higher reaction temperature will accelerate the hydrocracking, coke deposition on catalyst would increase as a side reaction. Our previous study found that Zn + P doped NiMo/γ-Al₂O₃ catalyst could reduce the coke deposition and suppress catalyst deactivation. Therefore, we investigated Zn + P doped Co/Mo catalysts for MHC of VGO to suppress coke deposition. In addition, P, Zn and Zn + P doped γ-Al₂O₃ supports were prepared to evaluate the acidity and hydrogen activation ability on these surfaces. Deactivation of Zn + P doped catalyst was more suppressed than that of the P doped catalyst. Zn may decrease the number of Brønsted acid sites and improve hydrogen activation ability. The naphtha content in the product oil from Zn + P doped catalyst was less than that for P doped catalyst. Lower naphtha yield probably depended on the reduced number of Brønsted acid sites. Furthermore, the product oil from Zn + P doped catalyst had a lower aromatic content. Hydrogenation of the feedstock was promoted because Zn additive increased the activation of hydrogen. These characteristics all depended on the surface properties.

We previously reported that the reductive conversion of 2-chloropropene (2-PEN) on γ-alumina-supported palladium catalysts showed high activity at 348 K. However, 2-chloropropane (2-PAN), propylene, and propane were produced non-selectively in this catalyst system, so industrial development would require separation process. In the present study, an alumina-supported nickel catalyst achieved a highly selective conversion of 2-PEN to propylene. For example, the propylene selectivity reached 95.7 % and conversion of 2-PEN was 15.0 % on the catalyst loaded with 10 % nickel at 473 K. However, the propylene yield was only 14.3 %, so the reaction was examined at 623 K, which resulted in 75.6 % conversion of 2-PEN and 78.6 % selectivity to propylene, with an adequate 59.4 % yield. Importantly, no propane was produced under these conditions, eliminating the need to separate propane and propylene. We concluded that by using nickel as a catalyst, an excessive reduction of propylene to propane could be suppressed.

Improvement in the dehydrogenations of ethane, propane, and isobutane over alumina-supported nickel oxides occurs together with the formation of large amounts of carbon deposits with time-on-stream, but catalyst activity is decreased with an additional increase in time-on-stream. This improvement in activity is due to metallic nickel formation that is highly dispersed over carbon nanotube-like deposits. However, the activity decreases as this highly dispersed metallic nickel is further covered with carbon deposits. We describe the use of oxygen treatment to regenerate the catalyst. Oxygen treatment to remove carbon deposits generally results in a less active catalyst due to sintering of the active species. However, we speculated that sintered nickel oxide could form carbon nanotubes in the proposed system, and that the formation of highly dispersed nickel over the nanotubes would regenerate the catalyst. To prove this hypothesis, dehydrogenations of ethane, propane, and isobutane were investigated using 18, 15, and 20 % nickel oxide supported on γ-alumina, respectively. We confirmed regeneration of the catalytic activity via oxygen treatment during subsequent dehydrogenations.

Heavy hydrocarbons, such as coal tars and petroleum residues are inexpensive raw materials for the manufacture of carbon fiber. Average molecular structural analysis is a useful technique to derive average structural models of these heavy hydrocarbons. These models are conventionally determined based on elemental composition, average molecular weight, and nuclear magnetic resonance (NMR) spectroscopy. However, laboratory preparations sometimes fail to provide sufficient sample quantities for NMR analysis, and some samples may not dissolve in solvents. We have developed an alternative approach for estimation of the average molecular structural parameters of heavy hydrocarbons using infrared (IR) spectroscopy which requires only small sample quantities (1-2 mg) and can accommodate insoluble materials. The equations that predict the parameters, i.e., the carbon aromaticity, molar ratios of terminal methyl groups to aromatic carbon, molar ratios of methyl groups to the sum of the methyl and methylene groups, and oxygen contents of ketones and carboxylic acids, were determined using IR spectra and hydrogen-to-carbon atomic ratios of various samples such as coal, asphaltene, and/or model compounds.

Fe₅C₂ has been widely used as a catalyst in CO₂ hydrogenation to produce useful compounds because of its high activity for C–C bond formation. Since the formation of Fe₅C₂ usually requires the prolonged pretreatment of iron oxide with H₂ or syngas (CO + H₂), catalysts that efficiently form Fe₅C₂ during CO₂ hydrogenation are desirable. In this study, we developed alkali metal-doped Fe₂O₃-supported Ru catalysts that efficiently formed Fe₅C₂ during CO₂ hydrogenation and suppressed the selectivity of hydrocarbons, especially methane, compared to Ru/Fe₂O₃. After the reaction, Fe₅C₂ formation from Ru/Fe₂O₃ was more efficient with K, Rb, and Cs than with Li and Na coexisting. Various characterizations for K–Ru/Fe₂O₃ demonstrated that the supported Ru nanoparticles were covered by in situ formed Fe₅C₂. The efficient formation of Fe₅C₂ during CO₂ hydrogenation, the coverage of Ru nanoparticles by Fe₅C₂ and the formation of a Ru core-Fe₅C₂ shell structure could be attributed to the synergistic effects of iron oxide reduction promoted by Ru-mediated hydrogen spillover and the enhancement of dissociative CO adsorption by alkali metals.

Paired Al sites were formed in high-silica MFI-type zeolite frameworks with Si/Al molar ratios of 11-13 via the transcription-induced method, where Al-rich amorphous silica–alumina enriched with paired Al species was employed as a zeolite precursor. Quantification by the Co²⁺ titration technique demonstrated that the aging time for the precursor in synthesis gels prior to the hydrothermal treatment was the key to controlling the amount of paired Al sites in the MFI-type frameworks. Ultraviolet-visible spectra of the Co²⁺-exchanged MFI-type zeolites indicated that the paired Al sites captured bare Co²⁺ without any oxygen-containing ligands and also that most of the paired Al sites were present at the channel intersections of the MFI-type framework.

A binary Ni₃Ga intermetallic catalyst was tested for the dry reforming of benzene. The combination of X-ray diffraction and X-ray absorption fine structure analysis confirmed the formation of the Ni₃Ga intermetallic structure. Moreover, alloying Ni with Ga considerably enhanced CO₂ utilization, and the CO₂ conversion was two times that of the monometallic Ni catalyst. Ga plays a crucial role in improving catalytic activity and minimizing coke formation.